The present disclosure describes methods of manufacturing printed circuit boards and devices that may be used to regulate electrical characteristics of printed circuit boards. When manufacturing a printed circuit board it may be desirable to connect electronic components on the top surface of the printed circuit board to conductive paths on top of or within the printed circuit board. These conductive paths may themselves extend to other electrical components attached to the printed circuit board, whether passive components such as capacitors or resistors, or active components such as integrated circuit chips. An electrical component may be attached to a printed circuit board by first drilling a small hole or opening in the printed circuit board and fastening the component by applying solder to mate the electronic component to the printed circuit board and form an electrical connection. In some circumstances, a wire part of an electrical component may be inserted into the opening to facilitate formation of the electrical connection.
The upper portion of the conductive path extends between the top of the printed circuit board and the level of an internal electrical connection point and is part of the minimum-path electrical circuit connection between an electrical component on top of the printed circuit board and the internal electrical connection, extending to downstream electrical components also attached to the printed circuit board. Stubs, or portions of wire or solder that extend beyond the minimum-path electrical circuit may be formed during printed circuit board manufacturing processes. Stubs may be removed from the printed circuit board by drilling or other processes that remove them from within the printed circuit board, truncating their branch in the electrical circuit while leaving the upper portion of the conductive path intact.
Stubs may hinder optimum performance of printed circuit boards. When transmitting a signal across a printed circuit board, transmission speed and transmission clarity may be significant factors in overall board performance. A stub or other portion of an electrical circuit may create configurations where signals transmitted through the wire bifurcate into an original signal that may travel down the intended pathway and a reflected signal that may travel down a branch in the electrical circuit and reflect back to follow the original signal. The delay between the original signal and the reflected signal may cause noise in the signals within the printed circuit board and may slow the response of components attached to the printed circuit board or the data transmitted from the printed circuit board to a computing device where the board is installed.
Reflected signals may be eliminated by drilling out portions of the printed circuit board. When a stub is removed by drilling, typically from the backside of a printed circuit board, the back drilling process may create an array of holes in layers of the conductive plane layers of printed circuit boards used to transmit power across the printed circuit board. These holes may reduce the power transmission efficiency of a printed circuit board and may merit the use of higher voltages or higher currents to achieve desired performance levels of the printed circuit board.